Shape memory alloy vibration isolation device

ABSTRACT

Methods and apparatus for mitigating the effects of vibration of various tools, such as those used downhole, by utilizing a vibration isolation device that incorporates Shape Memory Alloys (SMAs). For instance, in some embodiments, a vibration isolation device may be designed and deployed in a manner such that, when a vibration isolation device is operated in an expected manner, the force on the SMAs from static loading is sufficient to induce partial phase transformation between the austenite and martensite phases. This partial phase transformation may result in a reduced stiffness of the vibration isolation device in comparison to a tool in either a full austenite phase or full martensite phase.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/844,033, filed Sep. 12, 2006.

BACKGROUND

1. Field of the Invention

Embodiments of the present invention generally relate to isolating and reducing vibrations generated by the operation of downhole tools, such as those used in the exploration, production, and/or processing of hydrocarbons.

2. Description of the Related Art

Vibrations are often encountered at various times when exploring for, producing, and processing hydrocarbons. Vibrations may affect not only the performance of tools, but may also cause these tools to fail prematurely if the vibrations are sustained or extreme. One application where vibrations present particular challenges is when drilling subsurface wells with a drill bit at the end of a rotating drill string.

When drilling a wellbore, two main sources of vibrations are typically present. First, vibrations may be generated at the face of the drill bit in contact with the rock formation being drilled. The amplitude of these vibrations may be particularly high when drilling through hard rock formations. Second, vibrations may be generated in the drill string due to the rotation of the drill string. Vibrations may lead to different undesirable effects, such as reduced rate of penetration of the drill bit, damage to sensitive downhole tools (e.g., electronic components), as well as reduced life of and/or damage to the drill bit, and fatigue of the drill string.

Different approaches have been used in efforts to mitigate vibrations and their effect on downhole tools. One approach has been to control the drilling process to avoid combinations of certain parameters, such as rotary speeds and values of weight-on-bit (WOB), that result in harsh or sustained vibrations. Unfortunately, this approach is somewhat limited because the parameters or combination of parameters that lead to excessive vibration for a given bottom hole assembly (BHA) may not be known. In addition, it may be necessary to change the rotary speed and/or the weight-on-bit in an effort to maintain a desired rate of penetration during drilling operations, which may result in inadvertent entry into a combination of parameters causing large vibrations.

Another approach to reducing drill string vibrations is to use specialized drill string components, commonly referred to as “shock subs,” as part of the drill string. While different designs of shock subs are available, they typically have a spring element with low stiffness compared to the stiffness of the drill string, which reduces acceleration forces and include some type of damping mechanism to dissipate the kinetic energy. These shock subs are typically located close to the drill bit to reduce vibration transmission from the drill bit to the drill string. Some types of shock subs may perform reasonably well in reducing the axial vibrations, but unfortunately, their effect on lateral vibrations is not consistent and tends to vary for different shock sub designs. In fact, some shock subs may actually increase lateral vibrations.

Thus, an enhanced technique and mechanism for reducing vibrations, such as those encountered in hydrocarbon exploration, production, and/or processing operations, is needed.

SUMMARY OF THE INVENTION

Embodiments of the invention generally provide techniques for reducing the adverse effects of vibration.

In a first embodiment, an apparatus for reducing vibrations in well operations is described. The apparatus generally includes a body member formed at least partially of a shape memory alloy material and one or more connectors for connecting the apparatus between a first component and a second component.

In a second embodiment, an excavating system is described. The excavating system generally includes an excavating member, a component coupled to the excavating member and adapted to provide power to the excavating member, and a vibration isolation device coupled to the excavating member and the component. The vibration isolation device is generally positioned to reduce vibrations transmitted from the excavating member to the component during drilling operations and generally includes a body member formed at least partially of a shape memory alloy material.

In a third embodiment, a method for isolating vibrations in a wellbore is described. The method generally includes disposing a vibration isolation device at least partially formed of a shape memory alloy material between an excavating member and a component. Then, the excavating member is supplied power by the component, wherein loading on the vibration isolation member is sufficient to induce a partial phase transformation of the shape memory alloy material.

In a fourth embodiment, a method associated with the production of hydrocarbons is described. The method comprises providing a wellbore; disposing a vibration isolation device at least partially formed of a shape memory alloy material between an excavating member and a rotation component; and rotating the excavating member by the rotation component with loading on the vibration isolation device sufficient to induce at least a partial phase transformation of the shape memory alloy material.

In a fifth embodiment, a method of fabricating a vibration isolation device is described. The method comprises selecting a shape memory alloy (SMA) material that exhibits superelasticity within a range of temperatures in which the vibration isolation device is expected to be operated; determining a range of one or more forces to which the vibration isolation device is expected to be subjected during operation; calculating one or more dimensions of the vibration isolation device based, at least in part, on the determined range of temperatures and the determined range of forces; and fabricating the vibration isolation device according to the calculated dimensions using the selected SMA material. In addition, the method may also include utilizing the vibration isolation device in excavating operations to reach a subsurface formation and/or producing hydrocarbons from the subsurface formation.

In a sixth embodiment, a method of producing hydrocarbons is described. The method comprises disposing a vibration isolation device at least partially formed of a shape memory alloy material between an excavating member and a rotation component; forming a wellbore adjacent to a subsurface reservoir with the excavating device; rotating the excavating member by the rotation component with a weight on the vibration isolation device sufficient to induce a partial phase transformation of the shape memory alloy material; and producing hydrocarbons from the subsurface reservoir via the wellbore.

In a seventh embodiment, another excavating system is described. The excavating system may include an excavating member; a plurality of components operatively coupled to the excavating member and adapted to provide power to the excavating member; and a plurality of vibration isolation devices. Each of the plurality of vibration isolation devices are coupled between one of two of the plurality of components and the excavating member and one of the plurality of components, wherein each of the plurality of vibration isolation devices are positioned to reduce vibrations transmitted from the excavating member to the plurality of components during drilling operations and has a body member at least partially formed of a shape memory alloy material. Also, each of the plurality of vibration isolation devices may be selected to facilitate vibration mitigation for different temperature/strain regimes in this embodiment.

In one or more of the embodiment, various features may be further described. For example, the shape memory alloy material may be selected such that force on the body member due to static loading is sufficient to induce partial phase transformation between an austenite phase and a martensite phase of the shape memory alloy material when the apparatus is operated in an expected manner; may be selected to exhibit superelasticity in an expected temperature range in which the apparatus is to be operated; may include one of Nickel-Titanium, Copper-Zink-Aluminum, Nickel-Titanium-Copper, and Copper-Aluminum-Beryllium and any combination thereof; may be selected such that lower frequency vibrations are dampened to a greater extent relative to higher frequency vibrations; and/or may be selected to exhibit superelasticity in an expected temperature range. Further, the one or more connectors may be at least partially formed of the shape memory alloy material and treated to reduce the superelasticity relative to superelasticity of the body member; may be formed from a material substantially different than the shape memory alloy material. The body member may be designed so that force on the body member, which may be due to static and dynamic loading, is sufficient to induce partial phase transformation between an austenite phase and a martensite phase of the shape memory alloy material. Also, the first component may be a rotating member, such as a drill bit, and the second component, such as a drill string, may be coupled to the rotating member. Further, vibration isolation device may be formed as a tubular member that allows drill fluid to flow from the drill string to the drill bit through the tubular member.

Further still, in one or more of the embodiments, other aspects may be further described. For instance, in some embodiments, the loading may comprise quasi-static loading, such as weight on the vibration isolation device or weight-on-bit, and dynamic loading, such as loading generated from vibrations of the excavating member. Further, some embodiments may include incorporating the vibration isolation device in a bottom hole assembly containing the excavating member; connecting the vibration isolation device in line with the component via threaded connections; the excavating member being a drill bit; and when the drill bit is operated with an expected weight-on-bit, the force on the body member due to static loading is sufficient to induce partial phase transformation between an austenite phase and martensite phase of the shape memory alloy material; the temperature of the vibration isolation device being changed to induce a more favorable stress/temperature regime for the shape memory alloy material to facilitate vibration dampening; the component being coiled tubing and providing power to the excavating member comprises providing hydraulic power to the excavating member; wherein the component is a remotely operated drilling device and providing power to the excavating member comprises providing power to the excavating member to rotate a shaft in the remotely operated drilling device; receiving the power in the excavating member to perform percussion drilling; and/or the rotating of the excavating member being rotating casing; and/or the excavating member being rotated as an underreaming operation to expand the wellbore.

Moreover, some embodiments may include other features. For instance, some embodiments may include the body member being fabricated into a tubular member having a central opening for fluid flow through the vibration isolation device; the shape memory alloy material being selected such that lower frequency vibrations are dampened to a greater extent relative to higher frequency vibrations; fabricating a body member at least partially of a shape memory alloy material and fabricating one or more connectors secured to the body member for connecting the vibration isolation device with components; the body member being fabricated into a tubular member having a central opening for fluid flow through the vibration isolation device; treating the one or more connectors to reduce the superelasticity relative to superelasticity of the body member; and/or the one or more connectors being formed from a material substantially different than the shape memory alloy material.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention and some of its advantages can be better understood by reference to the following detailed description, considered in connection with the accompanying drawings, wherein:

FIG. 1 illustrates an exemplary drilling assembly having a shape memory alloy (SMA) vibration isolation device positioned between a bottom hole assembly and a drill string in accordance with one embodiment of the present invention;

FIG. 2 is a stress-temperature phase diagram for an exemplary shape memory alloy (SMA) suitable for use with embodiments of the present invention;

FIGS. 3A and 3B are diagrams illustrating super-elastic stress-strain response for an exemplary SMA suitable for use with embodiments of the present invention;

FIG. 4 is a diagram illustrating the change in the damping with vibrations amplitude for an exemplary SMA suitable for use with embodiments of the present invention; and

FIG. 5 is a flowchart of exemplary operations for designing and using a SMA vibration isolation device in accordance with embodiments of the present invention.

DESCRIPTION OF THE INVENTION Introduction and Definitions

Embodiments of the present invention provide methods and apparatus that may be used to mitigate the effects of vibration of various tools, such as downhole tools, by utilizing a vibration isolation device incorporating a shape memory alloy (SMA) material. For some embodiments, the vibration isolation device, which may be referred to as an SMA “damper”, may be designed and deployed to utilize static loading during expected operation to induce partial phase transformation from austenite to martensite. This partial phase transformation may result in reduced stiffness compared to a tool or component in either the austenite or martensite phase completely.

Accordingly, when the vibration isolation device is subjected to additional loading due to vibrations, the lower stiffness of the SMA material may reduce the force transmissibility between associated coupled components based on the partial phase transformation. That is, energy from the additional loading due to vibrations may be consumed by phase transformation of the SMA material in the vibration isolation device, rather than be transmitted to components.

As used herein, the term shape memory alloy (SMA) generally refers to a metal that exhibits properties generally referred to as the shape memory effect and superelasticity (also known as pseudoelasticity). Various types of SMAs that may be suitable for use as described herein include, but are not limited to NiTi (Nickel-Titanium), CuZnAl (Copper-Zink-Aluminum), NiTiCu (Nickel-Titanium-Copper), and CuAlBe (Copper-Aluminum-Beryllium), or any combination thereof. The particular composition or ratio of each element for any particular alloy may be selected based on the desired properties for a given application.

The shape memory effect refers to the ability of an SMA to return to its original shape after it has been deformed therefrom. In some situations, an SMA may return to its original shape via heating and/or during unloading (from a superelastic state). This effect is due to a temperature-dependent phase transformation between a low-symmetry crystallographic structure (known as martensite) to a high-symmetry crystallographic structure (known as austenite). Further explanation of the underlying physics resulting in the SMA properties is provided in Otsuka et al., Wayman et al. and Funakubo et al. See, e.g., Otsuka, K., and Wayman, C. M. (Eds.), Shape Memory Materials, Cambridge University Press, Cambridge, (1999); Wayman, C. M. Phase Transformations, Nondiffusive, In: Cahn, R. W., Haasen, P. (Eds.), Physical Metallurgy. North-Holland Physics Publishing, New York, pp. 1031-1075, (1983); Funakubo, H. (Ed.), Shape Memory Alloys. Gordon Breach Sci. Pub., New York, (1987).

The temperatures at which the martensite and austenite phases start and finish forming, respectively, may be represented by the following variables: M_(S), M_(F), A_(S), and A_(F). These temperatures are dependent on the particular composition of the SMA and are typically known and provided by a vendor of the SMA. Superelasticity generally occurs when the SMA is completely composed of material in austenite phase (i.e., at temperature is greater than A_(F)). As the load on the SMA is increased, material in the austenite phase transforms into the martensite phase because of the loading. The temperatures and strain at which the SMA changes its crystallographic structure are characteristic of the particular SMA selected, and can be tuned by varying elemental ratios and/or thermomechanical treatment.

As used herein, the term drill string generally refers to a combination of a drillpipe, a bottomhole assembly (BHA), and any other tools used to make an excavating member (e.g., a drill bit, underreaming device, or other type of device suitable for removing earth formation) rotate or turn at the bottom of the wellbore (e.g., a mud or electric motor). Drillpipe generally refers to tubular elements fitted with special threaded ends to connect rig surface equipment with the bottomhole assembly and the drill bit, allowing drilling fluid to be pumped to the drill bit and allowing the drill bit to be raised, lowered and rotated. Bottom hole assembly generally refers to a lower portion of the drill string including the drill bit, bit sub, a mud motor (in certain applications), stabilizers, drill collars, heavy-weight drillpipe, jarring devices (“jars”), and various other components.

To facilitate understanding the following description refers to a vibration isolation device having SMA materials positioned to reduce vibrations transmitted between a drill bit and a drill string as a specific, but not limiting, example of a useful application. However, those skilled in the art will recognize that a vibration isolation device of the type described herein and/or utilized in the manner described herein may be used to mitigate the effects of vibration in a wide variety of applications involving a wide variety of different tools.

These applications may include various drilling techniques, for example, using casing as the drill string, coiled tubing, as well as applications where there no drill string is used, but rather a bottom hole assembly deployed on wireline, or any other type of rotating member or rotation component. An SMA vibration isolation device as described herein may also be used in an autonomous drilling apparatus, for example, to isolate vibrations transmitted between a drill bit and a remotely operated drive motor or other type equipment (such as logging equipment used to measure downhole parameters while drilling). An SMA vibration isolation device, as described herein, may also be used in other types of applications utilizing rotating members that generate vibrations, such as underreaming, where the diameter of an existing borehole is expanded.

EXEMPLARY EMBODIMENTS

Referring first to FIG. 1, an exemplary drilling assembly 100, in accordance with one embodiment of the present invention, is shown. As illustrated, the drilling assembly 100 may include a vibration isolation device 101 having shape memory alloy (SMA) material. The vibration isolation device 101 includes a body 102 formed at least partially of any suitable SMA and connectors 104. The vibration isolation device 101 may be positioned between a bottom hole assembly 110 and a drill string 120. As illustrated, the vibration isolation device 101 may be threaded in line with the drill string 120 via connectors 104, which are described in greater detail below. The connectors 104 may be designed to not exhibit the same characteristics as the body 102. For some embodiments, rather than a conventional drill string, the vibration isolation device 101 may be used to reduce vibrations transmitted from an excavating member, such as a drill bit 112, to some other type of drive component, such as a drive shaft in a remotely operated (robot) drilling device.

In general, the vibration isolation device 101 may be positioned at any location suitable to dampen vibrations generated when penetrating the Earth with the drill bit 112. As an example, the vibration isolation device 101 may be part of the drill string 120 or threaded in line with the drill string 120 (as shown). As another example, the vibration isolation device 101 may be part of the bottom hole assembly 110, for example, in the form of a drill collar or near-bit component (e.g., located at, near, or between stabilizers 114). Regardless, by placing the vibration isolation device 101 adjacent to or near the bottom hole assembly 110, the vibration isolation device 101 may reduce the amount of vibrations transmitted between the drill string 120 and the bottom hole assembly 110, as well as the vibrations transmitted between the drill bit 112 and the drill string 120.

As described in greater detail below, the vibration isolation device 101 may be designed, such that during the vibration loading or the operating temperature expected during operation, the body 102 undergoes at least a partial phase transformation. Thus, in this exemplary application, the properties of the particular SMA material chosen for use in the body 102, as well as the dimensions of the vibration isolation device 101 (e.g., inner diameter, outer diameter, and length), may depend on a number of factors, such as the expected weight-on-bit and rotational speed of the drill string which may determine the longitudinal strain and rotational strain (torque), respectively. Other factors that may determine the selection of the actual SMA material may include an expected range of temperatures (e.g., expected downhole temperatures) in which the device 101 operates and the materials (e.g., drilling and production fluids) to which the device 101 is exposed.

At least two types of loading may be considered or utilized in the design of the vibration isolation device 101 to mitigate vibrations. The weight-on-bit in the axial direction results in a quasi-static loading, while the string rotation results in constant torque. An additional type of loading is dynamic loading due to axial, lateral and/or torsional vibrations. To enhance vibration isolation, the vibration isolation device 101 may be designed such that, at the expected operating temperature downhole, the force due to static loading is sufficient to induce partial phase transformation of the SMA material from austenite to martensite.

Further, the temperature near the vibration isolation device 101 may also be adjusted to facilitate mitigate of vibrations by adjusting the temperature in the vibration isolation device 101. To adjust the temperature, fluids of different temperatures may be passed through or around the vibration isolation device 101 or an electrical heating/cooling device may be used. The temperature change may result in the SMA operating in a more favorable temperature/strain regime.

FIG. 2 illustrates a stress-temperature phase diagram, which may be referred to by reference numeral 200, of an exemplary SMA material. As mentioned above, the SMA material is characterized by four specific temperatures illustrated along a temperature axis 260 of the phase diagram 200: martensitic start (M_(S)), martensitic finish (M_(F)), austenitic start (A_(S)) and austenitic finish (A_(F)). As shown in the phase diagram 200, at low levels of stress (e.g., along a lower portion of stress axis 250) and high temperatures (higher than A_(F)), the SMA material is in the austenite phase, while at high levels of stress and/or low temperatures the SMA material is in the martensite phase. The phase transformation between these two phases is called martensitic phase transformation.

As illustrated, the temperatures at which transformation from the martensite phase to austenite phase begins and ends depends on the level of stress applied to the SMA material, as indicated by the martensitic start and finish lines 206 and 208, respectively, which define an austenite-to-martensite transformation region 210. Similarly, the temperatures at which transformation from austenite phase to martensite phase begins and ends also depend on the level of stress, as indicated by the austenitic start and finish lines 204 and 202, respectively, which define a martensite-to-austenite transformation region 220.

As described above, one of the behaviors exhibited by SMA materials is superelasticity. While the material behaves as martensite at temperatures below M_(F), superelastic behavior is observed during loading and unloading at temperatures above A_(F). The superelastic behavior is associated with stress-induced martensitic phase transformation and reversal to the austenite phase upon unloading. An example of a superelastic “loading path” 230 as a function of stress in an isothermal example is shown in the phase diagram of FIG. 2. As can be observed by following the loading path 230, the SMA material undergoes a transformation to the martensite phase as stress is increased, followed by a transformation back to austenite phase as the stress is reduced. This phase transformation may be particularly beneficial, as it may serve to dampen vibrations by consuming (at least a portion on the corresponding energy that may otherwise be transmitted between tools or components.

FIGS. 3A and 3B are exemplary schematic diagrams of stress versus strain for the shape memory alloy material of FIG. 2, in accordance with embodiments of the present techniques. In this diagram of FIG. 3A, which may be referred to by reference numeral 300, the stress versus strain response resulting from superelastic loading is schematically illustrated as three distinct regions, which are the martensite phase, austenite phase, and transformation region, against a stress axis 350 and a strain axis 360. The transformation region includes the conversion from martensite-to-austenite phase and the conversion from austenite-to-martensite phase. The amount of recoverable transformation strain may depend on the composition and treatment of the shape memory alloy. As previously described, these shape memory alloys may include Nickel-Titanium (NiTi), Copper-Aluminum-Zinc (CuAlZn), Nickel-Titanium-Copper (NiTiCu), Copper-Aluminum-Nickel (CuAlNi), and any other suitable metal alloy. Typically, the amount of recoverable transformation strain for these shape memory alloys may range between about 3% to about 8%.

During the loading process, the shape memory alloy behaves in an elastic manner, as shown in the austenite elastic line 302. When a threshold stress level is reached (as indicated by point 303 on the stress axis 350), the transformation stage begins. As the loading continues to increase along an austenite-to-martensite transformation line 304, the transformation strains are generated during conversion of the shape memory alloy from the austenite phase to the martensite phase. When the shape memory alloy has transformed completely into the martensite phase, as shown by the martensite elastic line 306 that begins at point 305 along the stress axis 350, the shape memory alloy behaves in an elastic manner of the martensite phase and continues this behavior as loading is increased until, eventually, permanent deformation occurs. Preferably, the SMA material for the vibration isolation device is selected such that permanent deformation occurs at a point well outside the values of stress and strain expected during normal operation.

During the unloading process, the shape memory alloy again behaves in an elastic manner that is consistent with the martensite phase, as shown in the martensite elastic line 306. When a threshold stress level, such as indicated by point 307 along the stress axis 350, is reached, the reverse transformation stage begins for the conversion from martensite-to-austenite phase, as shown by second transformation line or martensite-to-austenite transformation line 308. As the stress on the shape memory alloy is further reduced, the shape memory alloy may reform into its previous structure. When the shape memory alloy has transformed completely into the austenite phase (past point 309), as shown by the austenite elastic line 302, the shape memory alloy behaves in an elastic manner of the austenite phase.

During a superelastic loading-unloading cycle, a portion of the mechanical energy that is used for phase transformation is converted to heat and dissipated. The dissipated energy is equal to the shaded area 310 inside the stress-strain loop shown in FIG. 3A (i.e., the path along austenite-to-martensite transformation line 304 and one of the martensite-to-austenite transformation line 308 or a partial martensite-to-austenite transformation line 312). In a vibration isolation device, such as the vibration isolation device 101 shown in FIG. 1, this dissipated energy may correspond to a reduction in energy of vibrations transmitted from the drill bit 112 to the drill string 120.

The outer loop exhibiting hysteresis shown in FIG. 3A (defined by complete paths along austenite-to-martensite transformation line 304 and the martensite-to-austenite transformation line 308) is commonly referred to as a major transformation loop. In a major transformation loop, sufficient stress is applied to cause the material to undergo a complete transformation from the austenite phase to the martensite phase and a reverse transformation (as the stress is reduced) from the martensite phase to the austenite phase. When the SMA material experiences a partial transformation (e.g., due to a limited fluctuations of stress resulting from high frequency vibrations) minor transformation loops may occur. For instance, minor transformation loops (i.e., partial transformations) may occur during forward phase transformation from austenite to martensite if the stress is reduced. Such a minor loop may follow the path from the austenite-to-martensite transformation line 304 to a partial martensite-to-austenite transformation line, such as one of the 312 ₁-312 _(n) lines, where n may be any integer number. Another type of minor loops may occur during reverse transformation from martensite to austenite, as schematically shown in FIG. 3B. During unloading when the material follows martensite-to-austenite path 308 if the stress is increased, a minor loop occurs, which may follow one of the lines 314 ₁-314 _(n). Taking into account both of the above cases, partial transformation may occur at any point between complete martensite and austenite phases if the direction of the stress change is reversed.

As noted above, at least two types of loading components may be considered when designing and/or deploying a vibration isolation device, such as the vibration isolation device 101. The first type of loading component is quasi-static loading, resulting from weight-on-bit in the axial direction and a constant torque due to string rotation. The second type of loading component is dynamic loading due to vibrations, such as axial, lateral and/or torsional vibrations. Accordingly, to enhance the effectiveness of the vibration isolation device, it may be designed such that the force due to static loading is sufficient to induce partial phase transformation between the austenite phase and the martensite phase for the portion of the vibration isolation device made from SMA material.

This partial phase transformation is shown in the diagram 400 of FIG. 4, which is plotted in terms of force 450 versus displacement 460. In the partial phase transformation, the effective stiffness of the SMA material in the vibration isolation device is lower than the elastic stiffness of SMA material completely in the austenite or martensite phases. As a result, when the vibration isolation device is subjected to additional (dynamic) loading due to vibrations, the lower stiffness may result in a reduction of the force transmissibility between the components or elements coupled to the vibration isolation device 101, which may include the drill bit 112 and the rest of the drill string 120. In addition, during vibration loading the SMA material continues to transform, which results in damping, and thus reducing the kinetic energy transmitted through the vibration isolation device.

With the SMA material in the vibration isolation device, its properties give a vibration isolation device an advantage over traditional isolation devices because of the phase transformation. For example, traditional vibration isolation devices utilize spring elements, which have problems with resonant behavior at low frequencies, due to low stiffness of the spring elements. While some traditional vibration isolation devices may include additional damping elements (possibly in an effort to alleviate this problem), these damping elements add cost and complexity and may degrade the response of the vibration isolation devices at higher frequencies.

The vibration isolation device of the present embodiments utilizes the properties of the SMA material to enhance vibration isolation over other techniques. For example, for a fixed value of the acceleration, high frequency dynamic stresses (e.g., due to vibration) may result in low amplitude (small displacement) vibration as shown by minor transformation loops 404. These minor transformation loops 404 introduce very little damping, as indicated by the relatively small area enclosed by the minor transformation loops 404. However, for low frequencies with the same value of acceleration, the amplitude of the vibrations are larger (larger displacement), which result in larger transformation loops 406. These transformation loops 406 provide larger damping from the vibration isolation device. Thus, unlike the response of traditional vibration isolation devices, with SMA vibration isolation devices, larger damping may occur at lower frequencies, which typically correspond to higher amplitudes, while less damping occurs at higher frequencies, which typically correspond to lower amplitudes.

The high and low frequency responses are provided by the inherent properties of the SMA material operating in the superelastic regime. In addition, these effects occur not only during axial loading, but also during bending and torsion of the vibration isolation device. Thus, in addition to axial vibrations, lateral and torsional vibrations may also be reduced by the embodiments of the vibration isolation device.

As a result of the material properties, a vibration isolation device formed with an SMA material may provide adequate response without the use of separate spring and damping elements. For some embodiments, the vibration isolation device may be formed as a relatively simple structure, such as a tubular element in-line with, or as part of, a drill string or bottom hole assembly. Such a simple mechanical structure may be beneficial because it has does not have moving parts, which may enhance reliability.

As described above, enhanced vibration damping may be achieved by operating the vibration isolation device in a superelastic regime (e.g., as close as possible to a major transformation loop). Thus, in some cases, an isolation device may be designed with a particular SMA that exhibits superelasticity under the expected operating conditions (e.g., downhole temperature and weight-on-bit) of the isolation device.

For some embodiments, an SMA vibration isolation device may be combined with conventional vibration isolation devices, such as shock subs. Further, other embodiments may include multiple SMA vibration isolation devices coupled together or distributed along an area to optimize dampening effects. In this manner, the vibration isolation devices may be designed to operate for different loads and placed in different locations based on the expected vibrations during operation. Further, this embodiment may enable the operations, such as drilling operations, to continue for larger distances as the loading and temperatures influence the phase of the SMA material in the vibration isolation devices. Accordingly, the multiple isolation devices may include the same or different material and/or dimensional properties to gain a desired effect. Further, for some embodiments, different SMA materials may be used within the same device and/or SMA materials may be combined with non-SMA materials. That is, each of the vibration isolation devices may be selected to facilitate vibration mitigation for different temperature/strain regimes.

To manufacture a vibration isolation device having SMA material in accordance with embodiments of the present invention, a number of parameters may be considered, as discussed in FIG. 5. FIG. 5 is a flow diagram 500 of an exemplary process for designing vibration isolation device incorporating SMA material. Those skilled in the art will recognize that the process is for exemplary purposes, as some operations may be optional, performed in a different order, and additional operations may also be performed.

The operations begin, at block 502, by determining an expected range of downhole temperatures. The expected range of temperatures may be determined based on historical data (e.g., previously logged) or via simulation and/or modeling. At block 504, a SMA material may be selected that exhibits superelasticity within the expected range of downhole temperatures. The transformation temperatures of a specific SMA may depend on factors, such as chemical composition, heat treatment and/or cold work.

At block 506, an expected range of weight-on-bit and torque values are determined. As with the expected range of temperatures, these values may be determined based on historical data (e.g., previously logged) or via simulation and/or modeling. At block 508, inner and outer dimensions of the SMA isolation device may be calculated based on the expected range of weight-on-bit and torque values. To calculate these dimensions, the operational temperatures, WOB and torque values should be estimated and the stress-temperature phase diagram (e.g., as shown in FIG. 2) may be used. Any suitable technique, such as computer modeling and/or simulations may also be utilized to calculate these dimensions. For some embodiments, inner dimensions may be determined by a desired bore that is to be maintained, for example, to allow the flow of drill fluids through the vibration isolation device without interruption. That is, the inner diameter may be substantially the same as the drill string or components coupled to the vibration isolation device.

At block 510, the length of the isolation device is calculated based on expected ranges of vibration frequency and amplitude. As with the other dimensions, any suitable technique, such as computer modeling and/or simulations may be utilized to calculate the lengths. Due to the potentially high cost of SMA materials, in some cases, blocks 508 and 510 may be performed in an iterative process in an effort to limit the total amount of SMA material used and associated cost.

In blocks 512-516, the design of the vibration isolation device may be fabricated and utilized. At block 512, the design of the vibration isolation device may be stored on a computer. The storage may include writing the design into memory of a computer system, writing the design of the vibration isolation device onto a portable memory, or printing the design of the vibration isolation device. At block, 514, the vibration isolation device may be fabricated based on the stored design. The fabrication may include treating the SMA to achieve desired properties, forming the material to the desired shape and dimensions (e.g., via machining, molding, or any other suitable techniques). At block 516, the vibration isolation device may be utilized in excavating operations to reach a subsurface formation. These operations may include drilling operations, such as drilling a wellbore to access subsurface formation, or other operations, such as under reaming a section of wellbore. Once accessed, the hydrocarbons may be produced from the subsurface formation at block 518.

To make SMA material selection and dimension calculations such that during vibration loading the SMA material undergoes partial phase transformation, detailed numerical and experimental studies for a variety of particular shape memory alloys under consideration may be performed. Such numerical studies may involve building a mathematical model of a drill string and other drilling equipment along with a vibration isolation device. The modeled drill string, drilling equipment and vibration isolation device may then be subjected to vibration loading. In addition, or as an alternative, an actual physical model (e.g., with full-scale or scaled-down dimensions) may be constructed. Regardless, the models may be generated in an effort to accurately represent the response of the SMA material under the anticipated operating conditions.

When designing connectors for the SMA vibration device, it may be desirable that the connectors do not exhibit superelasticity. For example, when designing connectors (such as connectors 104 in FIG. 1) used to connect the vibration isolation device inline with, at, or near a drill string or bottom hole assembly, superelasticity may reduce integrity of the desired connection to a rigid member or component. One approach to avoid superelasticity of the connectors may be to heat treat the portion of the SMA device used for connection, in a manner that reduces its superelastic properties. Another approach may be to have the connections manufactured from a non-SMA material, such as steel, and mechanically joined to the SMA portion of the device. A combination of these approaches may also be used, for example, manufacturing the connections from a non-SMA material that is then coupled to a treated portion of the SMA.

Embodiments of the present invention may be utilized to reduce the adverse effects of vibration, such as that generated by a component or tool in operation. While an SMA vibration isolation device positioned to reduce vibrations transmitted between a drill bit and a drill string has been described in detail above, those skilled in the art will recognize that a vibration isolation device of the type described herein and/or utilized in the manner described herein may be used to mitigate the effects of vibration in a wide variety of applications involving a wide variety of different tools, including, but not limited to, a variety of different type drilling applications and underreaming. With such applications, it may be possible to select a shape memory alloy that exhibits superelasticity as described herein in the expected range of operating conditions.

Further, in another embodiment, the vibration isolation device may be used in operations involving percussion (e.g. hammer) drilling methods. In percussion drilling, the drill string and the drill bit may not rotate because the power or energy is hydraulically or pneumatically supplied to the drill bit. With the percussion drilling, the vibration isolation device may be positioned above the drill bit and used to minimize vibrations transmitted from the drill bit to the drill string and surface equipment during percussion drilling.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. An apparatus for reducing vibrations in well operations comprising: a body member formed at least partially of a shape memory alloy material; and one or more connectors for connecting the apparatus between a first component and a second component.
 2. The apparatus of claim 1, wherein the shape memory alloy material is selected such that force on the body member due to static loading is sufficient to induce partial phase transformation between an austenite phase and a martensite phase of the shape memory alloy material when the apparatus is operated in an expected manner.
 3. The apparatus of claim 1, wherein the shape memory alloy material is selected to exhibit superelasticity in an expected temperature range in which the apparatus is to be operated.
 4. The apparatus of claim 1, wherein the one or more connectors are at least partially formed of the shape memory alloy material and treated to reduce the superelasticity relative to superelasticity of the body member.
 5. The apparatus of claim 1, wherein the one or more connectors are formed from a material substantially different than the shape memory alloy material.
 6. The apparatus of claim 1, wherein the shape memory alloy material comprises one of Nickel-Titanium, Copper-Zink-Aluminum, Nickel-Titanium-Copper, and Copper-Aluminum-Beryllium and any combination thereof.
 7. The apparatus of claim 1, wherein the shape memory alloy material is selected such that lower frequency vibrations are dampened to a greater extent relative to higher frequency vibrations.
 8. The apparatus of claim 1 wherein the first component is a rotating member and the second component is coupled to the rotating member.
 9. The apparatus of claim 8, wherein the rotating member is a drill bit and the component is a drill string.
 10. The apparatus of claim 9, wherein the force on the body member due to static loading is sufficient to induce partial phase transformation between an austenite phase and a martensite phase of the shape memory alloy material.
 11. The apparatus of claim 9, wherein the apparatus is formed as a tubular member that allows drill fluid to flow from the drill string to the drill bit through the tubular member.
 12. The apparatus of claim 8, wherein the shape memory alloy material is selected to exhibit superelasticity in an expected temperature range.
 13. The apparatus of claim 8, wherein the one or more connectors are formed substantially of material that is substantially different than the shape memory alloy material.
 14. A method for isolating vibration in a wellbore comprising: disposing a vibration isolation device at least partially formed of a shape memory alloy material between an excavating member and a component; and providing power to the excavating member by the component, wherein loading on the vibration isolation device is sufficient to induce a partial phase transformation of the shape memory alloy material.
 15. The method of claim 14, wherein the loading comprises quasi-static loading and dynamic loading.
 16. The method of claim 14, wherein the quasi-static loading comprises weight on the vibration isolation device.
 17. The method of claim 14, wherein the dynamic loading comprises loading generated from vibrations of the excavating member.
 18. The method of claim 14, wherein disposing the vibration isolation device between the excavating member and the component comprises incorporating the vibration isolation device in a bottom hole assembly containing the excavating member.
 19. The method of claim 14, wherein disposing the vibration isolation device between the excavating member and the component comprises connecting the vibration isolation device in line with the component via threaded connections.
 20. The method of claim 19, wherein the threaded connections are formed of a shape memory alloy material treated to have reduced superelasticity when compared with a body portion of the vibration isolation device.
 21. The method of claim 14, wherein the excavating member is a drill bit; and when the drill bit is operated with an expected weight-on-bit, the force on the body member due to static loading is sufficient to induce partial phase transformation between an austenite phase and martensite phase of the shape memory alloy material.
 22. The method of claim 14, wherein the temperature of the vibration isolation device is changed to induce a more favorable stress/temperature regime for the shape memory alloy material to facilitate vibration dampening.
 23. The method of claim 14, wherein the component is coiled tubing and providing power to the excavating member comprises providing hydraulic power to the excavating member.
 24. The method of claim 14, further comprising receiving the power in the excavating member to perform percussion drilling.
 25. A method of fabricating a vibration isolation device, comprising: selecting a shape memory alloy (SMA) material that exhibits superelasticity within a range of temperatures in which the vibration isolation device is expected to be operated; determining a range of one or more forces to which the vibration isolation device is expected to be subjected during operation; calculating one or more dimensions of the vibration isolation device based, at least in part, on the determined range of temperatures and the determined range of forces; and fabricating the vibration isolation device according to the calculated dimensions using the selected SMA material. 